poc-scale testing of oil agglomeration techniques …/67531/metadc... · poc-scale testing of oil...

POC-SCALE TESTING OF OIL AGGLOMERATION TECHNIQUES

AND EQUIPMENT FOR FINE COAL PROCESSING

Quarterly Technical Progress Report No. 9

January 1, 1998 - March 31, 1998

Principal Investigators

W. Pawlak

K. Szymocha

April 1998

Work Performed Under Contract No. DC-A22-95PC95152

Prepared by

Alberta Research Council

Environmental Technologies

250 Karl Clark Road

Edmonton, Alberta

Canada T6N 1E4

i

DISCLAIMER

*This report was prepared as an account of work sponsored by an agency of the UnitedStates Government. Neither the United States Government nor any agency thereof, nor anyof their employees, makes any warranty, express or implied, or assumes any legal liabilityor responsibility for the accuracy, completeness, or usefulness of any information,apparatus, product, or process disclosed, or represents that its use would not infringeprivately owned rights. Reference herein to any specific commercial product, process, orservice by trade name, trademark, manufacturer, or otherwise does not necessarilyconstitute or imply its endorsement, recommendation, or favoring by the United StatesGovernment or any agency thereof. The views and opinions of authors expressed herein donot necessarily state or reflect those of the United States Government or any agencythereof*.

ii

ABSTRACT

This report covers the technical progress achieved from January 1, 1998 to April 31, 1998on the POC-Scale Testing of Oil Agglomeration Techniques and Equipment for Fine CoalProcessing.Experimental work was carried out with two coal fines. One sample originated from pond(Drummond Pond Fines) while the second was pulverized Luscar Mine coal. Both sampleswere tested at the laboratory batch-scale while only Luscar Mine Coal was processed onthe 250 kg/h continuous system.Significant progress was made on optimization of process conditions for Pond Fines. Thetest results showed that ash could be reduced by about 42% at combustible recovery exiting94%. It was also found that pond fines required significantly longer conditioning time thanfreshly pulverized run of mine coal.Continuous bench-scale testing carried out with Luscar Mine coal included rod millcalibration, plant equipment and instrumentation check-up, and parametric studies.Compared with batch-scale tests, the continuous bench-scale process required morebridging oil to achieve similar process performance.During the current reporting period work has been commenced on the final engineering andpreparation of design package of 3t/h POC-scale unit.

iii

EXECUTIVE SUMMARY

During the current reporting period the batch- and pilot plant-scale experiments werecarried out. The batch-scale experiments were performed with Drummond Pond Fines andLuscar Mine coal. The objectives of batch testing were to improve coal fines recovery andto further optimize the process conditions. It was found that for the Drummond Pond Finesthe Aglofloat process performance might be improved by addition of some chemicals. Highrecovery of coal from the Pond Fines was possible with the combustibles recoveryapproaching 90% and ash reductions of about 45%. However, the Pond Fines required arelatively long conditioning time. It was also confirmed that the Luscar Mine coal ischaracterized by a very fast process kinetics and reduction of the conditioning time down to1 min would be feasible.

A series of the pilot plant tests were carried out with Luscar Mine coal, with a high-shearmixer as a conditioner, to establish the baseline performance for 250 kg/h continuous unit.These data are necessary and will be utilized as a reference for future tests with the jetprocessor. There were also some batch verification tests carried out with coal slurry takenfrom the pilot plant during continuous tests with Luscar Mine coal. The specific objectiveof these tests was to evaluate and compare process performance for both, batch- and bench-scale systems using exactly the same feed material. The tests performed revealed thatcontinuous pilot plant performance is slightly below that predicted from batch tests in termsof coal matter recovery, but better in terms of the quality of the coal product.

iv

Table of ContentsPage

Disclaimer ............................................................................................................ iAbstract ............................................................................................................... iiExecutive Summary ............................................................................................. iii1.0 Introduction .............................................................................................. 1

2.0 Laboratory Batch-Scale Testing................................................................. 22.1 Drummond Pond Fines Evaluation ................................................. 2

2.1.1 Influence of Oil Concentration on Process Performance...... 22.1.2 Influence of Conditioning Time on Process Performance.... 52.1.3 Influence of Selected Chemicals on Processing of

Pond Fines.......................................................................... 72.2 Evaluation Luscar Mine Coal ......................................................... 92.3 Batch Test Conclusions .................................................................. 14

3.0 Bench-Scale Testing - Mill Calibration ..................................................... 153.1 Bulk Coal Sample Description and Preparation .............................. 153.2 Rod Mill Calibration ...................................................................... 16

4.0 Pilot Plant Tests with Luscar Coal ............................................................. 204.1 Test L-1-Pilot Plant Operation Check-up........................................ 234.2 Pilot Plant Testing at Nominal Capacity and Low Oil

Concentration (Test L-2) ................................................................ 244.3 The Aglofloat Process Performance at Medium Oil

Concentration (Test L-3) ................................................................ 264.4 The Aglofloat Process at High Oil Concentration (Test L-4) .......... 294.5 Pilot Plant Performance and Comparison with

Batch-Scale Equipment. ................................................................. 324.6 Conclusions ................................................................................... 34

5.0 Flow Diagrams and Material Distributions for POC-Scale Equipment ....... 35

6.0 List of Abbreviations and Acronyms ......................................................... 41

Appendix

List of Figures

v

2-1. Influence of Oil Concentration and Type of Bridging Liquid on ProcessPerformance for Pond Fines....................................................................... 4

2-2. Influence of the Conditioning Time on the Process Performancefor Pond Fines ........................................................................................... 6

2-3. Influence of Additives on Process Performance for Pond Fines.................. 82-4. Process Performance for Luscar Mine Coal................................................ 112-5. Separation Curve for Luscar Mine ............................................................. 112-6. Washability Curve for Luscar Mine Coal ................................................... 13

3-1. Particle Size Distribution for Different Rod Charges.................................. 173-2. Rod Mill Calibration Curve at Mill Capacity of 190 kg/h........................... 183-3. Changes in Particle Distribution During Three Hour

Operation Period (Rod Charge 150 kg,Capacity 190 kg/h) ......................... 19

4-1. Flow Diagram of the ARC Pilot Plant Adapted for this Project .................. 214-2. Process Performance for Test L-3 .............................................................. 284-3. Process Performance for Test L-4 .............................................................. 314-4. Comparison of the Aglofloat Process Performance with Washability Data. 32

5-1. Simplified Flow Diagram on the Aglofloat POC-Scale Unit – Case A ....... 385-2. Simplified Flow Diagram of the Aglofloat POC-Scale Unit – Case B ........ 395-3. Simplified Flow Diagram of the Aglofloat POC-Scale Unit – Case C

Settling Pond Fines Treatment ................................................................... 40

List of Tables

2-1. Matrix Used for Pond Fines Testing........................................................... 32-2. Influence of Oil Addition on Process Performance for Pond Fines ............. 42-3. Influence of Conditioning Time on Process Performance for

Pond Fines................................................................................................. 52-4. Influence of Additives on Process Performance for Pond Fines.................. 72-5. Test Matrix for Luscar Mine Coal.............................................................. 92-6. Batch Tests Results for Luscar Coal........................................................... 102-7. Float-Sink Separation Results for Luscar Mine Coal .................................. 12

3-1. Rod Mill Calibration Targets ..................................................................... 153-2. Rod Mill Calibration (Capacity of 190 kg/h) .............................................. 163-3. Rod Mill Grinding Stability Test Results ................................................... 18

4-1. Test Results with Luscar Mine Coal (Test L-1).......................................... 234-2. Particle size Distribution (Test L-1) ........................................................... 244-3. Test Results for Luscar Mine Coal at Low Oil Concentration (Test L-2).... 254-4. Particle Size Distribution (Test L-2) ......................................................... 254-5. Test Results for Luscar Mine Coal at Medium Oil

Concentration (Test L-3) ........................................................................... 264-6. Particle Size Distribution (Test L-3) .......................................................... 27

vi

4-7. Test Results for Luscar Mine Coal at High OilConcentration (Test L-4) ........................................................................... 29

4-8. Particle Size Distribution (Test L-4) .......................................................... 304-9. Flotation cells Product Distribution (Test L-4) ........................................... 324-10. Verification Batch Flotation Results (Test L-4).......................................... 334-11. Comparison of the Batch-Scale and Pilot Plant Equipment Performance ... 34

5-1. Streams Description for Case A (undensified cyclone overflow slurryused for treatment)................................................................................. 36

5-2. Streams Description for Case B (Thickener used to densifycyclone overflow before treatment)............................................................ 36

5-3. Streams Description for Case C (Thickener applied as the feeding slurry tank for Pond Fines)........................................................................ 37

1

1.0 INTRODUCTION

This report covers the technical progress achieved from January 1, 1998 to March 31, 1998, on theProof-of-Concept (POC) Scale Testing of Oil Agglomeration Techniques and Equipment for FineCoal Processing project, under FETC/DOE Contract No. DE-AC22-95PC95152.

The overall objective of this project is to develop and demonstrate oil agglomeration technologycapable of increasing the recovery and improving the quality of fine coal streams. Oilagglomeration techniques, and especially the Aglofloat process, can be successfully applied forprocessing coal fines below 150 µm (100Mesh). At the present time, oil agglomeration is performedin high-shear mixers. These devices are energy demanding and consist of moving parts, that resultsin higher maintenance costs. Replacement of the high-shear mixer with less costly and less energyintensive equipment could reduce both capital and operating costs for the oil agglomerationtechnology.

In the first stage of testing, the pilot plant, equipped with high-shear mixer, will be tested to obtainthe baseline process performance. The generated data will be compared with a special design jetprocessor. Both devices, with capacities of 3 t/h, will be operated in parallel at a commercial coalpreparation plant. The contractor has already entered into Host Agreement with DrummondCompany Inc., a coal mining company located in Alabama. Demonstration of POC-scale equipmentwill be carried out at the Shoal Creek Mine preparation plant.

The project work ranges from batch and continuous bench-scale testing through the design,commissioning, and field testing of POC-scale agglomeration equipment.

During the current reporting period there were activities relative to the following tasks:

• Task 1 – Project Planning and Management• Task 4 – Coal characterization and laboratory (batch) and bench-scale testing• Task 5 – Final engineering and Design of POC-Scale Equipment• Task 9 – Process Evaluation

The work on the remaining tasks is scheduled to commence in the next reporting periods.

2

2.0 LABORATORY BATCH-SCALE TESTING

During the current reporting period the batch-scale experiments were carried out with DrummondPond Fines and Luscar Mine coal. The objectives of the testing series were coal specific and wereas follows:• Drummond Pond Fines

- to improve coal fines recovery- further optimization of process conditions- to examine the effect of various additives on process performance

• Luscar Mine Coal- further optimization of process conditions- establishing of the process conditions for the bench-scale runs

There were also some verification (flotation only) tests carried out with coal slurries taken from thebench-scale unit during tests with Luscar Mine coal. The specific objective of these tests was toevaluate and compare flotation performance for both batch-scale and bench-scale operations usingexactly the same feed material. The latter experiments and the test results are presented in theSection 4.

2.1 Drummond Pond Fines Evaluation

The process conditions tested for processing of the Pond Fines coal is presented in Tables 2-1.Process products (clean coal and tailings) were dried, weighed and analyzed in order to determine:• process material balance• clean coal quality, and• minerals content in tailings

2.1.1 Influence of Oil Concentration on Process Performance

A series of experiments was carried out to evaluate the effect of oil concentration on processperformance. The process conditions and test results are presented in Table 2-2 and Figure 2-1.The oil concentration was in the range 0.015% to 5%. The lowest concentration was typical of thatused for standard froth flotation in the coal preparation industry.Analysis of test results showed the following:

• poor process performance for standard froth flotation conditions; yields of clean coal andtailings were almost the same and were characterized by similar ash contents; process could bedescribed as a partition but not separation

• an increase in oil addition from 0.5% to 5% improved process performance in terms ofcombustibles recovery and ash contents in the clean coal and tailings

• the ash reduction was stabilized at oil concentration of 3%

• tailings ash values only approached 50% for the highest Maya/Diesel additions but increasedsignificantly to over 65% for the Diesel only tests.

3

• the best results were achieved when diesel oil was used at concentration of 4% and 5% (thehighest combustibles recovery and ash reduction, and the lowest ash content in the clean coal)

Table 2-1. Process Conditions Used for Pond Fines Testing

Variable Tested Kind/Range

Bridging Oil

• Type Diesel Oil

Maya Crude & Diesel Oil (1:1 ratio by wt)

• Addition Diesel Oil: 4% and 5%

Maya Crude & Diesel Oil:

0.015%, 0.5%, 1%, 2%, 3%, 4% and 5%

High-Shear Mixer

• Solids Concentration 10%, 20% and 30% (dry coal basis)

• Mixing Intensity 1750 rpm

• Residence Time 1, 3, & 10 minutes

Flotation

• Solid Concentration 6.5% (dry coal fines basis)

• Mixing Intensity 1,100 rpm

• Frother MIBC at 45 g/t (0.1 lb/t)

Aerofroth 65 at 28 g/t (0.05 lb/t) and

at 40 g/t (0.1 lb/t)

• Residence Time 6 minutes

Additives• Surfactants Oleic Acid at 0.5%

O-cresol at 0.5%

• Minerals Depressant Calgon (NaPO3)6 at 0.05%

Urea at 0.5% & 1.0%

Tween 80 at 0.004%

Note: Bridging oil and chemicals addition are based on dry coal basis.

4

Table 2-2. Influence of Oil Addition on Process Performance for Pond FinesFeed Coal: Moisture 22.7 %, Ash 23.4%Process ConditionsHigh-Shear Mixer: 10 min, 1750 rpm Cs 30% Oil Maya Crude & Diesel (1:1)Flotation Cell: 6 min, 1100 rpm Cs 6.5% Frother MIBC 45 g/t

Test OilConcn

Yield Combust.Recovery %

ProductAsh

AshReduction

Tailings Ash%

DPF-49 0.015 53.5 53.8 22.9 1.8 24.3DPF-14 0.5 60.9 64.2 18.9 19.1 29.0DPF-15 1 65.1 69.2 17.9 23.5 33.6DPF-77 2 71.0 76.7 16.1 31.2 39.7DPF-17 3 74.2 82.0 13.7 41.2 46.9DPF-78 4 76.4 85.4 14.0 40.1 48.5DPF-79 5 74.9 82.4 13.4 42.7 47.4DPF-67 4* 83.5 90.7 11.9 49.2 65.3DPF-68 5* 83.9 93.6 12.9 44.9 71.2* Diesel oil used as a bridging liquid

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5

Oil Concentration, %

Ash

, %

Ash

Red

uctio

n, %

R

ecov

ery,

%

Rec., M&D

AR, M&D

Ash, M&D

Rec., D

AR, D

Ash, D

.

Figure 2-1. Influence of Oil Concentration and Type of Bridging Liquid on Process Performance for

the Pond Fines

5

2.1.2 Influence of Conditioning Time on Process Performance

A series of experiments was carried out to determine the influence of high-shear mixing residencetime on the combustibles recovery and ash reduction. A partial matrix of experiments wereperformed at:

• constant solids concentration of 15% and 30%• oil addition levels of 1%, 2%, 2.5% and 3%, and• conditioning times of three, six and ten minutes

Analysis of the test results presented in Table 2-3 and Figure 2-2 revealed the following:

• for each oil concentration the reduction in conditioning time resulted in lowering combustiblematter recovery

• this was especially true for lower oil addition (1% and 2%), while for 3% oil concentration therewas no significant impact of conditioning time on the recovery

• ash content of clean coal was lower for shorter conditioning time, however this was counterbalanced by reduced combustible recovery

• tailings ash values were unacceptably low• lower solids concentrations produced improved results.• for lower solids concentration, a similar impact of conditioning time on process performance

occurred• recovery of combustible matter was reduced from 85.1% to 76.5% and 70.4% when

conditioning time was decreased from 10 minutes to 6 and 3 minutes

Table 2-3. Influence of Conditioning Time on Process Performance for Pond FinesProcess Conditions

High-Shear Mixer: 1750 rpm Cs: 15% Oil: Maya Crude & Diesel (1:1)

Flotation Cell: 6 min, 1100 rpm Cs: 6.5% Frother: MIBC 45 g/t

Test MixerResidenceTime, min

Oil/SolidsConcen

%

Combust.Recovery

%

ProductAsh%

AshReduction

%

TailingsAsh%

DPF-15 10 1/30 69.2 17.9 23.5 33.6

DPF-45 3 1/30 50.9 17.0 27.3 28.2

DPF-16 10 2/30 76.4 16.9 31.2 39.9

DPF-46 3 2/30 61.1 14.6 37.4 33.4

DPF-17 10 3/30 82.0 13.7 41.2 46.9

DPF-47 3 3/30 81.0 12.9 44.9 47.5

DPF-58 10 2.5/15 85.1 13.0 44.3 55.7

DPF-59 6 2.5/15 76.5 12.4 47.0 43.0

DPF-60 3 2.5/15 70.4 13.4 42.6 44.3

6

50

55

60

65

70

75

80

85

90

95

100

0 10 20 30 40 50 60 70 80

Ash Reduction, %

Rec

over

y, %

Washability

Washability

Oil 1%, Cs 30%, 10 min

Oil 1%, Cs 30%, 3 min

Oil 2%, Cs 30%, 10 min

Oil 2%, Cs 30%, 3 min

Oil 3%, Cs 30%, 10 min

Oil 3%, Cs 30%, 3 min

Oil 2.5%, Cs15%, 3, 6 & 10min

Figure 2-2. Influence of the Conditioning Time on the Process Performance for Pond Fines

2.1.3 Influence of Selected Chemicals on Processing of Pond Fines

A series of experiments was carried out with various chemicals used as an additives. Selection ofthe additives was based on previous work carried out with various ranks of coals. Two classes ofadditives were used:

• surfactants (oleic acid and O-cresol)• minerals depressants/dispersants (Calgon, Tween 80 and urea)

7

The concentrations used were additive specific and ranged from minute amounts (Tween 80) to 1%(urea). The additives were added to the coal slurry prior to conditioning and mixing time was 2minutes. In order to have a base line for comparison, all tests were carried under the sameconditions as test DPE-16 which was considered as a reference test. Table 2-4 and Figure 2-3present the results achieved for this series of experiments.

Table 2-4. Influence of Additives on Process Performance for Pond Fines

Process Conditions

High-Shear Mixer: 10 min 1750 rpm Cs: 30% Oil: 2.0% Maya Crude & Diesel (1:1)


Test AdditiveYield

%

Combust.Recovery

%

ProductAsh%

AshReduction

%

TailingsAsh%

DPF-16/77 None 70.7 76.4 16.116.5

31.229.2

39.9

DPF-69 Oleic Acid 0.5% 51.8 54.2 17.418.1

25.422.6

28.0

DPF-70 Aerofroth 28 g/t * 86.0 94.8 14.915.3

36.134.5

69.2

DPF-71 Aerofroth 40 g/t * 86.8 95.1 15.415.8

33.932.3

71.4

DPF-72 Calgon 0.05% 77.4 87.8 12.312.6

47.546.1

59.1

DPF-73 Urea 0.5% 66.5 74.1 13.413.8

42.840.5

41.5

DPF-74 Urea 1% 68.4 76.0 13.714.1

41.439.7

42.7

DPF-75 O-Cresol 0.5% 82.3 92.1 13.613.9

41.940.5

65.5

DPF-76 Tween 0.0038% 65.9 74.0 12.613.0

45.944.2

40.8

Note: Ash content and ash reduction are presented on- clean coal oil basis (first line)- clean coal oil-free basis (second line)* MIBC not used for these tests

8

50

55

60

65

70

75

80

85

90

95

100

0 20 40 60 80

Ash Reduction, %

Rec

over

y, %

Washability

"

Maya-Diesel

Oleic Acid

Aerofroth 1

Aerofroth 2

Calgon

Urea 0.5

Urea 1.0

O-Cresol

Tween

Figure 2-3. Influence of Additives on Process Performance for Pond Fines

Analysis of the test results with additives and a comparison with the reference test (Maya-Diesel)revealed the following:

• presence of Calgon and O-cresol improved process performance in terms of combustiblesrecovery and ash reduction

• for O-cresol combustibles recovery was increased by 14.1% as compared with reference testwhile ash reduction reached 41.9% (reference test 27.8%)

• the best ash reduction was achieved for Calgon (by 19.7% as compared with reference test),however this was counter balanced by lower combustibles recovery as compared with O-cresol

• application of urea resulted in higher ash reduction as compared with reference test butcombustibles recovery was slightly lower than for reference test

9

• addition of oleic acid and Tween 80 resulted in the worse process performance when comparedwith reference

• the results achieved with O-cresol and Calgon at bridging addition of 2% are comparable withthe results that could be achieved at higher bridging oil addition of 4% and 5%; selection of theoption of lower oil addition plus additives versus higher oil addition without additives has to bebased on economics (cost of chemicals versus cost of bridging oil, availability) andenvironmental aspects

Beside of application of surfactants and depressants, frother MIBC was replaced with Aerofroth 65.For both frother concentrations (225 g/t and 450 g/t) the combustibles recovery was significantlyhigher than for MIBC (94.5% and 95.1% for Aerofroth 65 versus 78.5% for MIBC). However, thisimprovement in the coal recovery was not accompanied by a significant increase in ash reduction.It is considered to replace MIBC with Aerofroth 65, but the following should be done prior tomaking any decision:

- run a series of experiments to optimize oil concentration and frother addition- contact frother manufacturer and compare Aerofroth 65 cost and availability with MIBC

which is the most used frother in coal processing

2.2 Evaluation of Luscar Mine Coal

A series of optimization experiments was carried out with Luscar Mine coal. An influence ofbridging oil concentration, solids concentration and conditioning time on process performance wasinvestigated. Table 2-5 presents the conditions used for testing, while the findings for this series areshown in Table 2-6 and Figure 2-4.

Table 2-5. Test Conditions for Luscar Mine Coal

Variable Tested Kind/Range

Bridging Oil• Type Diesel Oil, Maya Crude & Diesel (1:1)

• Addition 0.015%, 0.075%, 0.5%, 1%, 2% & 2.5%(dry coal fines basis)

High-Shear Mixer• Solid concentration 20%, 30% (dry coal fines basis)

• Mixing Intensity 1750 rpm

• Residence Time 1, 3 & 10 minutesFlotation• Solid concentration 6% & 6.5% (dry coal fines basis)

• Mixing Intensity 1,100 rpm

• Frother MIBC at 45g/t (0.1 lb/t)

• Residence Time 6 minutes

10

Table 2-6. Batch Tests Results for Luscar Coal

Feed Coal: Moisture - 3.1%, Ash - 16.5%Process Conditions

High-Shear Mixer: 1750 rpm Oil: Maya Crude & Diesel (1:1)


TestOil

Concn%

Res.Timemin.

SolidsConcn.(a)

%

FeedAsh (c)

%

ProductAsh%

TailingsAsh%

Combust.Recovery

%

AshReduction

%

DPF-48 0.015 10 30/6.5 16.1 9.5 30.7 74.6 41.0

DPF-18 0.075 10 30/6.5 16.1 10.0 41.6 85.9 37.9

DPF-19 0.5 10 30/6.5 16.2 11.5 80.4 97.7 29.0

DPF-20 1 10 30/6.5 16.0 11.4 82.3 98.2 28.8

DPF-21 2 10 30/6.5 17.0 11.6 81.6 97.3 31.8

DPF-22 3 10 30/6.5 17.3 11.3 81.5 96.6 34.7

DPF-61 0.5 (b) 3 20/6 16.4 12.1 78.6 99.0 26.2

DPF-62 1 (b) 3 20/6 16.8 11.0 85.5 98.4 34.5

DPF-63 2 (b) 3 20/6 17.1 10.6 85.5 97.8 38.0

DPF-64 0.5 (b) 1 20/6 16.6 11.2 86.1 99.0 32.5

DPF-65 1 (b) 1 20/6 16.5 10.6 85.5 99.0 35.8

DPF-66 2 (b) 1 20/6 16.4 11.0 87.7 98.7 34.8(a) Conditioning solids concentration/flotation solids concentration(b) Diesel oil(c) Reconstituted ash

To obtain more information about Luscar Mine coal sample used for pilot plant runs the washabilitytest has been carried on. The float-sink results are presented in Table 2-7 and Figures 2-5 and 2-6.

11

0

10

20

30

40

50

60

70

80

90

100

0 0.5 1 1.5 2 2.5 3

Oil Concentration, %

A

sh R

educ

tion,

%

R

ecov

ery,

%

Rec., Cs 30%, 10min

AR, Cs 30%, 10 min

Rec., Cs 20%, 3 min

AR, Cs 20%, 3 min

Rec., Cs 20% , 1 min

AR, Cs 20%, 1 min

Figure 2-4. Process Performance for Luscar Mine Coal

Table 2-7. Float-Sink Separation Results for Luscar Mine Coal

Float SinkSpecificGravity

Yield

wt%

CMRecovery wt%

Ash*Cumulative

wt%

AshReduction

wt%

Yield

wt%Direct Cum. Direct Cum. Direct Com.

1.3 17.3 17.3 20.7 20.7 2.39 2.39 87.0 82.7

1.4 32.5 49.8 37.5 58.2 2.26 4.65 74.4 50.2

1.5 21.3 71.1 23.1 81.3 2.04 6.69 63.9 28.9

1.6 9.6 80.7 9.4 90.7 1.54 8.23 55.4 19.3

1.8 5.5 86.2 4.6 95.3 1.53 9.76 47.1 13.8

2.0 2.6 88.8 1.8 97.1 1.00 10.76 41.5 11.2

+2.0 11.2 100 2.9 100.0 7.62 18.38 0 0* Total ash content for this sample is 18.4%

12

0

10

20

30

40

50

60

70

80

90

100

1 1.2 1.4 1.6 1.8 2 2.2

Specific Gravity

Floa

ts P

erce

ntag

e

Figure 2-5. Separation Curve for Luscar Mine Coal.

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20

Ash Content , %

Com

bust

ible

Rec

over

y, %

Figure 2-6. Washability Curve for Luscar Mine Coal.

13

Evaluation of the results led to the following conclusions:

• standard froth flotation carried out at diesel oil addition of 0.015% provides the cleanest coal,however this was counter balanced by lower combustible matter recovery (74.6%)

• an increase in oil addition to 0.5% improved combustible matter recovery up to 97.7%, howeverthis was also accompanied by an increase on ash content in clean coal by 2% (from 9.5% forstandard flotation to 11.5% for Aglofloat)

• an increase of oil concentration did not affected process performance; the results were verysimilar to that obtained for 0.5% oil addition

• there was also noticed that both solids concentration and conditioning time did not have impacton process performance

• for this particular coal very good results in a batch-scale can be achieved at low oilconcentration of 0.5%, short conditioning of one minute and solids concentration up to 30%

14

2.3 Batch Test Conclusions

A number of batch tests confirmed the potential of Aglofloat process for coal cleaning. The resultsindicated that:

• Aglofloat process is an efficient coal cleaning technology for pond fines. The combustiblematter recovery might be as high as 87 to 92% with ash reduction of about 42 to 48%

• Pond fines require a relatively long conditioning time in the order of six to ten minutes

• The addition of surfactants substantially improves energy recovery with little sacriface in coalquality and greatly increases the ash content of the tailings

• For Luscar Mine coal process kinetics is very fast and in batch system might be reduced downto 1 min without deterioration of the process performance and product quality

• Combustibles recovery for Luscar Mine coal is very high and approaches 98% with ashreduction of 35%

15

3.0 BENCH-SCALE TESTING - MILL CALIBRATION

3.1 Bulk Coal Sample Description and Preparation

The bench-scale testing and optimization of the jet processor were carried out with Luscar Minecoal. This coal was selected on the assumption that the rank and properties are very similar to thecoal processed at the Shoal Creek Mine preparation plant (coal extracted from Mary Lee CoalGroup located at Warrior Coalfield, Alabama).

The bulk sample of coal was purchased from Cardinal River Coals Ltd. that operates the LuscarMine some 40 km (25 miles) south of Hinton, Alberta. The Luscar Mine is a series of open pits thatare worked principally by shovel-and-truck methods. The run-of-mine coal is hauled severalkilometers to the processing plant. The layout of the preparation plant is very similar to that ofShoal Creek Mine processing plant.

The 20-ton bulk sample of run-of-mine coal was taken directly from the mine production line andwas hauled to Thermo Design Engineering (TDE) of Edmonton. TDE, a subcontractor to theproject, carried out the primary crushing using a commercial size hammer crusher. The crushingreduced the top size of coal particles to below 3 mm. After crushing the coal sample washomogenized, bagged, drummed and inerted with nitrogen. The drums were then moved to theDevon Research Centre, the location of ARC’s coal laboratories and pilot plant.

3.2 Rod Mill Calibration

First runs on the 250 kg per hour testing facility were carried out to calibrate the rod mill. Existingcoal grinding system consists of hopper, weighing belt, rod mill and slurry holding tank. The milloperates in the wet mode at a solids (coal) concentration of 50%. The coal is fed to the mill via aweighing belt. The coal slurry is discharged from the mill over a 600 µm screen, where oversizematerial is separated and recycled to the mill. The coal slurry is pumped to the slurry holding tank.During typical agglomeration runs, the coal slurry is directed to the high-shear mixers. Forcalibration runs the configuration of the system was changed and coal slurry was fed to the vacuumdisc filter for coal dewatering. The coal slurry samples were taken from the tank slurry dischargeevery half an hour. The calibration runs were carried out for three rod charges: 100, 150 and 300kilograms. The selection of weight of rods was based on previous work carried out with the coalscharacterized by similar Hardgrove grindability index as the Luscar Mine coal. For each calibrationrun, a set of target values for top particle size, mass median diameter and coal slurry solidsconcentration was defined (see Table 3.1).

Table 3.1 Rod Mill Calibration Targets

Particle Mass Median Coal SlurryRods Charge Top Size Diameter Solids Concentration

kg µm µm wt%

100 600 125 50

16

150 300 100 50

300 150 50 50

Coal slurries collected during calibrations runs were analyzed for:

• particle size distribution (PSD) (wet screening)• mass median diameter (d50), and• coal slurry solids concentration

Table 3-2 and Figure 3-1 present the results of calibration runs performed with different rodcharges.

Table 3-2. Rod Mill Calibration (Capacity of 190 kg/h)

Sample S 200 Rod Charge, kg100 150 300

Particle Sizemm

Wt% Cum. %

Wt% Cum. %

Wt% Cum. %

- 0.038 25.4 25.4 29.1 29.1 43.2 43.2

0.038 - 0.045 2.4 27.8 2.7 31.8 6.2 49.4

0.045 - 0.063 7.7 35.5 6.6 38.4 10.7 60.1

0.063 - 0.090 9.6 45.1 11.3 49.7 9.2 69.3

0.090 - 0.106 3.8 48.9 6.9 56.6 11.8 80.1

0.106 - 0.150 12.3 61.2 14.3 70.9 11.0 91.1

0.150 - 0.180 5.6 66.8 7.4 78.3 5.5 96.6

0.180 - 0.250 14.2 81.0 9.9 88.2 3.4 100.0

0.250 - 0.355 11.1 92.1 7.9 96.1 - -

+ 0.355 8.9 100.0 3.9 100.0 - -

d 50 110 µm 91 µm 46 µm

Analysis of the results revealed the following:

• for 100 kg rods charge- the top size was as targeted (less than 600 µm)- the mass medium was 110 µm (target 125 µm)- the mill was operated at a slurry concentration of 51wt% (target 50%)

• for 150 kg rods charge- there was about seven percent of particles with size above the target (300 µm)- the mass medium diameter was 91 µm (target 100 µm)- the mill was operated at a slurry concentration of 44 wt% (target 50%)

• for 300 kg rods charge- there was 9.1% of particles with size above the target of 150 um

17

- the mass medium diameter was 46 µm (target 50 µm)- the mill was operated at a slurry concentration of 45 wt% (target 50%)

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350 400

Particle Size, um

Cum

ulat

ive

Perc

ent P

assi

ng

100 kg

150 kg

300 kg

Figure 3-1. Particle Size Distribution for Different Rod Charges

The achieved results were used for creation of the mill grinding calibration curve for Luscar Minecoal (see Figure 3-2)

An additional calibration run was carried out for rod charges of 150 kg to determine the grindingsystem performance in terms of its stability. The duration of the run was three hours and sampleswere taken every one-hour.

18

Table 3-3 and Figure 3-3 present the results of calibration run with rods charge of 150 kg. Thespecific objective of this test was to check the stability of the grinding system. The samples weretaken every hour and were described as 11:00, 12:00 and 13:00.

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350

Rods Charge, kg

Mea

n Pa

rtic

le S

ize,

um

.

Figure 3-2. Rod Mill Calibration Curve at Mill Capacity of 190 kg/h

Table 3-3. Rod Mill Grinding Stability Test Results

Sample S -200 Time

11:00 12:00 13:00

Particle Size Wt% Cum. % Wt% Cum. % Wt% Cum. %

- 0.038 22.5 22.5 24.9 24.9 25.4 25.4

0.038 - 0.045 2.70 25.2 2.37 27.3 2.40 27.8

0.045 - 0.063 7.42 32.6 7.52 34.8 7.66 35.4

0.063 - 0.090 8.62 41.3 8.62 43.4 9.60 45.0

0.090 - 0.106 4.62 45.9 3.96 47.4 3.77 48.8

0.106 - 0.150 13.6 59.5 12.3 59.7 12.3 61.1

0.150 - 0.180 5.61 65.1 5.65 65.4 5.57 66.7

0.180 - 0.250 13.8 78.9 12.9 78.3 14.2 80.9

0.250 - 0.355 12.4 91.2 12.2 90.4 11.1 92.0

+ 0.355 8.77 100 9.57 100 8.02 100

d 50 119.2 µm 115.2 µm 109.6 µm

19

Analysis of the results led to the following:

- the stability of the grinding system was satisfactory- coal particles mass median diameter was in the range from 109.6 µm to 119.2 µm

- coal particles size distribution were similar for all three samples analyzed; the distributioncurves had the same pattern, but some small difference between the size fraction wereobserved

The results of calibration runs were used for preparation of test conditions for the continuous,pilot plant runs.

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350 400

Particle Size, um

Cum

ulat

ive

Perc

ent P

assi

ng

11:00

12:00

13:00

Figure 3-3. Changes in Particle Size Distribution During Three Hours Operation Period

20

(Rods Charge 150 kg, Capacity 190 kg/h)

4.0 PILOT PLANT TESTS

The 250 kg/h pilot plant used for testing is located at the Devon Research Centre, Alberta where theARC team carried out batch- and bench-scale testing. Figure 4-1 shows pilot plant configurationused in bench-scale continuous testing.

The bench-scale tests were performed to evaluate the agglomeration equipment performance and toestablish the design assumptions for 3 t/h test POC unit. In parallel to pilot plant tests some batch-scale flotation verification tests were performed to determine scale-up factor. The first runs wereperformed with the high-shear mixer only in order to establish reference process performance datafor the pilot plant system. In next stage of testing a high-shear mixer and jet processor will be usedalternatively.

The tests were carried out at various oil concentrations that were described as:

• low oil concentration - range 0.1% to 1.0%• medium oil concentration - range 1.0% to 2.5%• high oil concentration - above 2.5%

Sampling Points

S-200 - feed coal slurryS-201 - coal slurry after conditioning (with oil)S-501 - clean coal concentrate (product) from flotation cellS-502 - tailings from flotation cell

21

Figure 4-1. Flow Diagram of the ARC Pilot Plant Adapted for this Project.

Thickener TK700

SlurryTankV 200

Rod MillG 170

CleanProduct

HighShearMixerM220

OilTank

Surfac-tant

Tank

Flotation Cell-F500

Jet Processor

WaterTankTK100

VacuumDisk FilterTank

Waste FilterCake

Make-upWater

FW-110

Water

Coal

Water

CF 140

OversizedFines

SettlingTank

FS-201

P-151

P-201

P200

P101

P100

S-200

FB-151

S-501

S-201

S-502

SP175

SP174

FW-116

FW117

Water

Water

FS-502P-153

FrotherTank

23

4.1 Test L-1 - Pilot Plant Operation Check-up

The major objectives of the initial pilot plant test were:

• check of the plant equipment and instrumentation operation• verification of the plant control system performance• instrumentation calibration

The plant operation was performed at coal throughput of 200 kg/h and at a low oil concentration(~0.5%). The results achieved showed satisfactory plant operation. Most of the system equipmentworked properly. Only the coal feeding system balance was not working properly and a manualoperation was required to perform the test. During this run it was established that flotation waterflow rate should not exceed 38 L/min in order to avoid flooding of the flotation cell.

Table 4-1 presents a summary of the test results obtained during the pilot plant check-up test andTable 4-2 shows the particle size distribution of pulverized feed coal. Analysis of the particle sizedistribution for the feed coal showed that the mean coal particle size was of 105 µm.

Table 4-1. Test Results with Luscar Mine Coal (Test L-1)

Target Process ConditionsMill Rods Charge 100 kg, Frother 180 g/tPlant Throughput 200 kg/h Oil Concentration 0.5%Flotation Cell Solids Concentration 6.4%

Sampling Oil Feed Slurry (S 200) Product (S 501) Tailings (S 502) Yield CM Ash

Time Concn Cs Ash* Cs Ash Cs Ash Rec. Red.

14:00 Start % % % % % % % % % %

14:30 0.54 18.0 18.1 - - - - - - -

15:00 0.52 16.3 17.8 7.7 12.6 5.1 22.8 49.0 52.1 29.2

15:30 0.53 17.6 18.2 15 10.8 5.6 27.1 54.6 59.5 40.7

* Ash content of the composite feed coal sample - 17.9%

The test L-1 revealed that at low oil addition in the order of 0.5%, process performance was verypoor and coal recovery did not exceed 60%.

24

Table 4-2. Particle Size Distribution (Test L-1)

Size FractionSample S-200

mm Wt% Cum.%- 0.038 27.1 27.1

0.038 - 0.045 2.0 29.1

0.045 - 0.063 7.2 36.3

0.063 - 0.090 9.1 45.4

0.090 - 0.106 4.8 50.2

0.106 - 0.150 7.1 57.3

0.150 - 0.180 4.5 61.8

0.180 - 0.250 13.1 74.9

0.250 - 0.355 11.7 86.6

+ 0.355 13.4 100.0

d50 105 µm

4.2 Pilot Plant Testing at Nominal Capacity and Low Oil Concentration (Test L-2)

The test L-2 objective was to determine the process performance at low oil concentration in termsof the qualitative system response and to determine the minimum oil concentration required forsatisfactorily process performance.

During this experiment the coal feeding rate was 250 kg/h and relatively high frother addition (600g/t) was applied. A special attention was made for a careful observation of flotation cellperformance. The froth formation was very poor and a significant amount of coal reported to thetailings.

At low oil concentration of about 0.4% a very poor process performance was confirmed. Therecovery of the combustible matter was in the order of 40% and ash reduction was about 50%.After increasing oil concentration to 0.93%, a significant improvement in the process was noticed.The recovery increased up to 90% and ash reduction was on the order of 47%. Significantly moreclean coal product was generated in the first cell than in the remaining five cells. Most of the systemequipment and control system instrumentation worked properly. Tables 4-3 and 4-4 present theresults obtained for test L-2.

In the test L-2 an increase of the median coal particle size was observed during the course of thetest. This was caused by higher than previously anticipated rod mill throughput.

25

Table 4-3. Test Results for Luscar Mine Coal at Low Oil Concentration (Test L-2)

Target Process ConditionsMill Rods Charge 100 kg, Frother 600 g/tPlant Throughput 250 kg/h Flotation Cell Solids Concentration 7.8%Oil Concentration Period 1 (10:30 - 11:45) - 0.4%

Period 2 (11:45 - 12:30) - 0.9%

Sampling Oil Feed Slurry (S 200) Product (S 501) Tailings (S 502) Yield CM Ash

Time Concn Cs Ash* Cs Ash Cs Ash Rec. Red.10:30 Start % % % % % % % % % %

11:00 0.41 25.6 18.2 8.0 10.5 6.4 23.1 39 42.7 42.3

11:15 0.40 28.4 17.7 - - - - - - -

11:30 0.42 28.1 18.8 8.3 9.2 7.1 24.0 35 39.1 51.1

11:45 0.93 27.8 19.1 - - - - - - -

12:00 0.94 28.9 18.3 27.4 10.7 3.7 36.7 70.8 77.4 41.5

12:30 0.91 27.9 17.9 31.5 9.4 1.9 56.9 82.1 90.6 47.5

*Ash content of the composite feed coal sample -18.1%


Luscar Coal, Rods Charge - 100 kg, Coal Feeding Rate 250 kg/h

Sample S-200Size Fraction 11:15 11:45

mm Wt% Cum.% Wt% Cum.%- 0.038 29.0 29.0 25.1 25.1

0.038 - 0.045 1.8 30.8 2.2 27.3

0.045 - 0.063 6.8 37.6 7.4 34.7

0.063 - 0.090 10.0 47.6 7.4 42.1

0.090 - 0.106 5.0 52.6 5.0 47.1

0.106 - 0.150 7.4 60.0 6.6 53.7

0.150 - 0.180 4.3 64.3 4.6 58.3

0.180 - 0.250 11.8 76.1 15.3 73.6

0.250 - 0.355 11.3 87.4 12.7 86.3

+ 0.355 12.6 100.0 13.7 100.0

d50 97 µm 123 µm

26

4.3 The Aglofloat Process Performance at Medium Oil Concentration (Test L-3)

The purpose of test L-3 was to evaluate plant performance at a medium oil concentration (about1.5%) and using the high-shear mixer as a conditioner. These data would be used as a reference forcomparison of the system performance when using the jet processor for coal conditioning. Anotherobjective of the test was to check system stability and process performance during prolongedoperation time. During this run some operational problems were experienced with the coal feedingsystem. An excessive moisture content caused hanging of the coal charge in feeding bin andreducing the feeding rate down to 190 kg/h. The process conditions and test results are shown inTable 4-5, Table 4-6 and Figure 4-5. During the three hour testing period only slight changes inprocess performance were noticed. After a stabilization period, the gray in color water laden withmineral matter was visible in the last two flotation cells. The coal matter recovery was in the orderof 86%, clean coal ash was about 8.1% and ash reduction was 55%. As compared with batch testresults for the same oil concentration (coal matter recovery 97%, product ash 11.5% and ashreduction of 30%, see Report No 6, p. 30) a significant discrepancy in process performance wasobserved. The main problem emerging from this observation was determination of what caused thesignificant differences between batch and pilot plant systems in terms of the Aglofloat processperformance. Two possibilities were taken into consideration. A first one that the coal conditioningstage in batch and continuous systems are not the same, and second that flotation cells performancefor both systems differs significantly.

To make a more in depth investigation of the flotation stage performance, the plant flotation celldischarge was modified and the existing froth discharge was replaced by six independent chutes.This new arrangement allowed the measurement of product distribution and quality independentlyfor each cell. Such a modification enabled more detailed information about performance of theflotation cell when process conditions are changed.

Table 4-5. Test Results for Luscar Mine Coal at Medium Oil Concentration (Test L-3)

Target Process ConditionsMill Rods Charge 100 kg, Frother 250 g/tPlant Throughput 190 kg/h Flotation Cell Solids Concentration 5.7%Oil Concentration Period (10:30 - 14:00) - 1.5%

Sampling Oil Feed Slurry (S 200) Product (S 501) Tailings (S 502) Yield C.M. Ash


11:00 1.29 17.7 16.7 29.6 7.88 1.69 47.0 77.7 85.8 52.8

11:30 1.64 14.5 19.1 26.3 7.94 1.75 52.7 75.2 85.5 58.3

12:00 1.45 16.3 19.3 30.0 8.12 1.79 54.0 75.7 86.2 57.9

12:30 1.41 17.0 18.6 28.1 8.30 1.89 52.4 76.6 86.3 55.4

13:00 1.50 15.8 18.0 27.2 8.69 1.67 51.5 78.2 87.1 51.8

13:30 1.39 16.9 17.5 27.9 8.14 1.68 49.5 77.3 86.1 53.6

27

14:00 1.10 16.8 16.2 26.0 7.75 2.01 48.2 79.1 87.1 52.2

*Ash content of the composite feed coal sample -17.6%


Size Fraction Sample S-200

mm Wt% Cum. %- 0.038 25.1 25.1

0.038 - 0.045 2.4 27.50.045 - 0.063 7.6 35.10.063 - 0.090 9.2 44.30.090 - 0.106 3.8 48.10.106 - 0.150 13.0 61.10.150 - 0.180 5.6 66.70.180 - 0.250 13.6 80.30.250 - 0.355 11.4 91.7

+ 0.355 9.3 100.0

d50 112 µm

28

0

10

20

30

40

50

60

70

80

90

100

10 11 12 13 14 15

Clock Time, hour

Ash

, %

Solid

s C

oncn

. % T

ail.

Ash

, %

Ash

Red

. %

R

ecov

ery,

%

Recovery

Ash Red.

Prod. Ash

Tail. Ash

Solids Conc.

Figure 4-2. Process Performance for Test L-3

29

4.4 The Aglofloat Process Performance at High Oil Concentration (Test L-4)

The objectives of test L-4 were as follow:

- determination of the pilot plant process performance at high oil concentration- investigation of the plant system response and stabilization time determination after

major process condition adjustments- comparison of the process performance of continuous pilot plant system and laboratory

batch system

The test L-4 consisted of three periods each lasting two hours (see Figure 4-6). Process conditionsfor test L-4 are shown in Table 4-7. During the first period oil concentration was about 2.9% andwas reduced down to 1.3% to 0.7% in the second period, and increased up to 2.5% in the thirdperiod. During each period, in addition to routine sampling, two extra samples of conditioned slurry(S-201) were taken from the system. These samples were used to perform independent batch-scaleflotation verification tests with exactly the same feed material as used in the pilot plant.

Table 4-7. Test Results for Luscar Mine Coal at High Oil Concentration (Test L-4)

Target Process ConditionMill Rods Charge 150 kg, Flotation Cell Solids Concentration 6%Diesel Oil Concentration Period 1 (9:30 - 11:30) - 2.9% MIBC Frother 250 g/t

Period 2 (12:15-14:15) - 1.3% - 0.7% "Period 3 (14:15-15:40) - 2.5% "

Sampling Oil Feed Slurry (S 200) Product (S 501) Tailings (S 502) Yield C M Ash


10:00 2.90 16.1 17.8 27.5 9.97 0.2 76.0 88.1 96.5 44.0

10:30 3.19 16.6 16.5 28.1 9.64 0.66 69.4 88.5 95.8 41.6

11:00 2.78 15.4 16.9 27.0 9.59 0.68 71.9 88.3 96.0 43.3

11:30 2.82 15.8 16.8 - 9.04 0.72 74.7 88.2 96.4 46.2

11:00-12:15 Changes implemented

12:30 1.01 11.3 17.0 18.8 8.37 0.98 51.2 79.8 88.2 50.8

12:45 1.32 11.3 15.4 20.8 7.64 0.74 55.0 83.6 91.3 50.4

13:00 1.38 12.3 17.0 19.2 7.84 0.95 55.0 80.6 89.5 53.9

13:45 0.85 19.5 20.1 24.3 7.88 3.41 44.6 66.7 76.9 60.8

14:15 0.88 18.5 20.6 15.2 10.80 5.78 22.7 17.6 17.7 47.6

14:16 Changes implemented

14:30 2.53 19.5 19.0 26.6 9.42 1.34 62.1 81.8 91.5 50.4

14:45 2.46 20.2 20.1 28.3 9.81 1.27 62.6 80.5 90.9 51.2

15:15 2.45 19.8 19.6 28.2 9.82 0.98 69.0 83.5 93.6 49.9

15:45 2.66 18.3 19.0 27.4 9.08 1.53 68.1 83.2 93.4 52.2 *Ash content of the composite feed coal sample -18.0%

30


Sample S 200

Size Fraction 13:05 15:15mm Wt% Cum. % Wt% Cum. %

- 0.038 31.2 31.2 27.5 27.5

0.038 - 0.045 1.6 32.8 1.7 29.2

0.045 - 0.063 10.8 42.6 7.6 36.8

0.063 - 0.090 11.6 55.2 14.0 50.8

0.090 - 0.106 7.5 62.7 2.6 53.4

0.106 - 0.150 13.9 76.6 11.3 64.7

0.150 - 0.180 5.7 82.3 6.9 71.6

0.180 - 0.250 10.4 92.7 13.2 84.8

0.250 - 0.355 5.4 98.1 9.4 94.2

+ 0.355 1.9 100.0 5.8 100.0

d 50 80.1 µm 88.9 µm

During the first period a steady plant operation was observed. The combustible matter recovery wasvery high, in the order of 96%, and ash reduction was about 45%. The clean coal product containedabout 9.5% of ash.

During the transition from the first to the second period some operational problems wereexperienced. Due to excessive coal moisture in the one of barrel, hanging of the coal charge infeeding bin occurred and as a result of that coal feeding system plugged. Because of coal feedingsystem disturbance, the coal slurry solids concentration in high-shear mixer has droppedsignificantly (down to 11%). After a countermeasure was taken in next 45 min achieved level ofabout 19%. During second period the oil concentration was reduced initially down to 1.3%, andnext down to 0.7% when evident deterioration in the process performance (flotation stage) wasobserved. The described process condition changes are evident in Figure 4-6. Because processconditions were not well established in the system during the second period, data for this periodshould be treated rather as a qualitative.

In third period the oil concentration was increased up to 2.5% and the test was continued for thenext two hours. The transition from the second period to a third period gave a very goodopportunity to study the system behavior and to evaluate the time required for the systemstabilization. From the results obtained it was concluded that one hour is a sufficient time tostabilize and to achieve the steady state performance of plant.

In the third period for the coal matter recovery was 93.5% and the ash reduction was 51%. Theseresults are in a good agreement with results obtained during the first period of operation.

31

0

10

20

30

40

50

60

70

80

90

100

9 10 11 12 13 14 15 16

Clock Time, hour

Ash

, % S

olid

s C

onc.

, %

A

sh R

ed.,

%

T

ail.

Ash

, %

Rec

over

y, %

Recovery

AR

Prod. Ash

Tail. Ash

Solids Concn

Batch Rec.

Batch AR

Batch T. Ash

Figure 4-3. Process Performance for Test L-4

32

Some preliminary data were also obtained for the flotation cell product distribution at different oilconcentrations (see Table 4-9). For high oil concentration most of the product (over 85%) is floatedin first two cells. For medium oil concentration this accounts only for about 65%.

Table 4-9. Flotation Cells Product Distribution (Test L-4)

Mass Distribution%

OilConcn

% Cell #1 Cell #2 Cell #3 Cell #4 Cell #5 Cell #6~1 42.5 22.3 16.6 8.3 7.9 2.4

2.8 66.2 19.1 5.2 3.7 3.5 2.3

4.5 Pilot Plant Performance and Comparison with the Batch-Scale Equipment

Data on pilot plant performance for the Luscar Mine coal and comparison of the Aglofloat processperformance with float-sink tests are shown in Figure 4-4.

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Ash Reduction, %

Com

bust

ible

s R

ecov

ery,

%

W ashability

Rec. Plant

Figure 4-4. Comparison of the Pilot Plant Aglofloat Process Performance with Washability Data

33

During the test L-4 three sets of the slurry samples (two for each period) were taken from the inletto the flotation cell. These samples were processed in the lab flotation cell using the proceduredeveloped for batch-scale tests. The result of the batch flotation tests for plant samples are presentedin Table 4-10 and Figure 4-3. Comparison of the batch scale and the pilot plant equipmentperformance is given Table 4-10.

Float-Sink tests were carried out with sample taken from plant (feed coal slurry was dewatered,dried and sent for testing). This approach guaranteed that comparison would be done for similarsamples. Recoveries achieved on the plant run were slightly below washability curve.

Table 4-10. Verification Batch Flotation Test Results (Test L-4)

Process Conditions

Diesel Oil Frother MIBC 250 g/t

Flotation Cell: 6 min, 1100 rpm, Cs 6.5%

Time OilConcn

%

H S MixerSolids Concn

%

Yield

%

Combust.Recovery

%

ProductAsh%

AshReduction

%

TailingsAsh%

10:35 2.85 16.4 90.0 97.3 9.9 42.5 77.9

11:35 2.85 15.4 90.4 96.9 10.1 39.7 79.2

13:15 ~1.0 13.5 83.3 91.0 9.1 46.4 55.3

13:40 ~0.85 16.5 73.5 83.6 8.7 56.8 51.1

15:15 2.45 19.4 87.7 96.3 10.9 44.3 77.1

15:40 2.66 19.4 88.0 96.4 10.6 44.0 75.8

* Higher frother addition (two times)

34

Table 4-11. Comparison of the Batch-Scale and Pilot Plant Equipment Performance

Test System OilConcentration

%

Feed CoalAsh%

CMRecovery

%

ProductAsh%

AshReduction

%

TailingsAsh %

10:35 Plant 2.85 16.5 95.8 9.6 41.6 69.4

10:35 Batch " 17.3 97.3 9.9 42.5 77.9

11:35 Plant 2.85 16.8 96.4 9.0 46.2 74.7

11:35 Batch " 16.8 96.9 10.1 39.7 79.2

13:05 Plant 1.3 17.0 89.5 7.8 53.9 55.0

13.15 Batch " 16.9 91.0 9.1 46.4 55.3

13:45 Plant 0.85 20.1 76.9 7.9 60.8 44.6

13:40 Batch " 20.1 83.6 8.7 56.8 51.1

15:15 Plant 2.5 19.6 93.6 9.8 49.9 69.0

15:15 Batch " 19.6 96.3 10.9 44.3 77.1

15:40 Plant 2.6 18.9 93.4 9.1 52.0 68.1

15:35 Batch " 19.0 96.4 10.6 44.0 75.8

The comparison of the pilot plant performance with verification batch test data seems to indicatethat the batch system generates products which are characterized by higher coal matter recovery,but lower ash reduction.

4.6 Conclusions

The pilot plant tests demonstrated the potential of Aglofloat technology for physical cleaning of theLuscar coal and revealed the following:

- significant reduction of ash at high energy recoveries

- energy recoveries of 85 % or greater measured against the feed coal energy content

- very good response of the system for process conditions change

- stabilization time for the pilot plant system is of the order of one hour

- batch system as compared with continuous pilot plant system gives a shift of data withincreased recovery, decreased ash reduction and high tailings ash; a very good correlationbetween batch results and pilot plant results was shown

35

- tailings ash content seems to be a very reliable process performance indicator.

36

5.0 FLOW DIAGRAMS AND MATERIAL DISTRIBUTIONS FOR POC-SCALEEQUIPMENT

The major objective of the project is process development, design and engineering, construction andoperation of a 3 t/h proof-of-concept (POC) Aglofloat test unit. Engineering design of the POC-scale unit, performed by Thermo Design Eng., begun February 1998 and will be completed byMay 31, 1998. After approval of the design package by DOE, the construction of the POC moduleis scheduled for the period June - August 1998.

During the course of work on the conceptual design and engineering, three process flow diagramswere developed:

• Case A - cyclone overflow without densification used as a plant feed• Case B - cyclone overflow densified to solids concentration of about 20% used as a plant feed• Case C - slurry prepared from pond fines used as a plant feed.

Simplified process diagrams are shown in Figures 5-1, 5-2, and 5-3. Each diagram presents majorcomponents of the module and identifies process streams and sampling points. For case A and B thefeed coal slurry is received from the Shoal Creek coal preparation plant. The slurry is taken fromthe cyclone overflow pipeline as a slipstream. For case B slurry will be densified in a smallthickener to achieve the slurry solids concentration of about 15% to 20%. It is assumed at this pointthat in case C the feed coal is received from the settling pond by truck and, after loading into mixingtank, diluted with water to obtain required solids concentration.

The POC process consists of three major operations. These are:

- coal slurry preparation (case B and C)- slurry conditioning- coal separation and recovery

Because of space limitation and the technical problems, the future 3 t/h POC module flotation cellwill have to be smaller (0.25 to 0.5 t/h) than the originally planned throughput. To accommodatethis change, only a part of the processed slurry will be taken to the flotation cell. The excess ofprocessed slurry will bypass the flotation system. In the conditioning stage, by contacting coalparticles with oil, coal aggregates are formed. A High-Shear mixer and Jet Processor are usedalternatively to mix bridging liquid with the coal slurry. In the flotation system these aggregates areseparated from mineral mater.

Based on the batch-scale testing, three sets of data were selected for the mass balances, calculationsthat were used for the Aglofloat POC-scale unit design.

37

Table 5-1. Streams Description for Case A (No densified cyclone overflow slurry used for

treatment).

StreamNo.

Stream Description Flow Ratem3/h

Flow Ratet/h

Solidst/h

Watert/h

Cs

%1 Cyclone Overflow 54.7 55.5 3 52.5 5.4

2 Flotation Cell Feed 4.61 4.68 0.25 4.43 5.3

3 Clean Coal 0.72 0.78 0.21 0.57 27

4 Flot. Cell Tailings 3.88 ~3.9 0.04 3.88 1

5 Slurry (bypass) 52.2 52.3 2.75 49.5 5.3

6 Discharged Slurry 4.68 4.75 0.25 4.5 5.3

7 Jet Processor Water 1.5 1.5 - 1.5 -

Table 5-2. Streams Description for Case B (Thickener used to densify cyclone overflow

before treatment).

StreamNo.

Stream Description Flow Ratem3/h

Flow Ratet/h

Solidst/h

Watert/h

Cs

%1 Cyclone Overflow 54.7 55.5 3 52.5 5.4

2 Flotation Cell Feed 1.61 1.68 0.25 1.42 15

3 Clean Coal 0.72 0.78 0.21 0.57 27

4 Flot. Cell Tailings 3.88 3.89 0.04 3.85 ~1

5 Slurry (bypass) 17.5 18.3 2.75 15.5 15



8 Densified Slurry 17.6 18.5 3.0 15.5 16.2

9 Thickener Water 37.3 37.1 0.2 37.0 0.5

10 Flotation Water 3.0 3.0 - 3.0 0

38

Table 5-3. Streams Description for Case C (Thickener applied as the feeding slurry tank

for Pond Fines)

StreamNo.

Stream DescriptionFlow Rate

m3/hFlow Rate

t/hSolids

t/hWater

t/hCs

%1 Water 17.5 17.4 -

2 Flotation Cell Feed 1.61 1.68 0.25 1.42 15

3 Clean Coal 0.72 0.78 0.21 0.57 27

4 Flot. Cell Tailings 3.88 3.89 0.04 3.85 ~1

5 Slurry (bypass) 17.5 18.3 2.75 15.5 15



8 Slurry 17.6 18.5 3.0 15.5 16.2

9 Thickener Water 37.3 37.1 0.2 37.0 0.5

10 Flotation Water 3.0 3.0 - 3.0 -

39

to PlantFlotation Cell

OilTank

Flotation Cell

High ShearMixer

FrotherTank

SlurrySplitterBox

SlurryTank

Jet Processor

CleanProduct

Tailings

WaterTank

from CyclonesOverflow~1200m3/h

Legend: - Flowmeter

S-2

- Pump

- Metering Pump

1

ConditioningTank

(Existing at ShoalMill Creak Plant)

S-3

2

6

4

7

5

3

Figure 5-1. Simplified Flow Diagram of the Aglofloat POC-Scale Unit - Case A.

S-1

41


OilTank

Flotation Cell

High ShearMixer

FrotherTank

SlurrySplitterBox

SlurryTank

Jet Processor

CleanProduct

Tailings

WaterTank

from CyclonesOverflow~1200m3/h

Legend: - Flowmeter

S-2

- Pump

- Metering Pump

1

SlurryDensifier

ConditioningTank


S-3

S-1

8

2

9

6

4

7

5

3

Figure 5-2. Simplified Flow Diagram of the Aglofloat POC-Scale Unit - Case B.

42

Figure 5-3. Simplified Flow Diagram of the Aglofloat POC-Scale Unit Case C - Settling Pond Fines Treatment.


OilTank

Flotation Cell

High ShearMixer

FrotherTank

SlurryTank

Jet Processor

CleanProduct

Tailings

WaterTank

Water

Legend: - Flowmeter

S-2

- Pump

- Metering Pump

1

SlurryDensifier

ConditioningTank


S-3

S-1

8

2

9

6

4

7

5

3

PondFines

44

6.0 LIST OF ABBREVIATIONS AND ACRONYMS

AR - ash reduction

concn - concentration

Cs - solids concentration in coal – water slurry (dry coal basis)

D - diesel oil

D&PDS - diesel oil with admixture of surfactant polydimethyl siloxane

MC&D - blend of Maya crude oil and diesel oil (1:1 ratio)

PDS - polydimethyl siloxane

rec - recovery

red - reduction

tail or T - tailings

45

Appendix A

46

Table A-1. Batch Tests Results

Test Feed CoalAsh&Moist

Oil MixType

OilAddition

%

MixerResTime

&rpm

Flot. CellResTime

&rpm

SolidsConcent.

%

Yield

%

Combust.Recovery %

Prod.Ash%

AshRed.%

FrothSolidsConcn

TailingsAsh%

DPF-58Pond

A 23.37% M 37%

Maya &Diesel (1:1)

2.5 101750

61100

15/6.5 75.9 85.1 13.013.45

44.342.4

11.2 55.74

DPF-59Pond

A 23.37% M 37%

Maya &Diesel (1:1)

2.5 61750

61100

15/6.5 68.1 76.5 12.3812.85

47.045.0

11.6 43.0

DPF-60Pond

A 23.37% M 37%

Maya &Diesel (1:1)

2.5 31750

61100

15/6.5 63.6 70.4 13.4113.95

42.640.3

10.3 44.3

DPF-61Luscar

A 16.8%M 3.01%

Diesel 0.5 31750

61100

20 93.4 99.0 12.1 28.0 15.6 78.6

DPF-62Luscar

A 16.8%M 3.01%

Diesel 1 31750

61100

20 92.2 98.4 11.04 34.4 17.45 85.5

DPF-63Luscar

A 16.8%M 3.01%

Diesel 2 31750

61100

20 91.4 97.8 10.56 37.2 20.46 85.5

DPF-64Luscar

A 16.8%M 3.01%

Diesel 0.5 31750

61100

20 92.8 98.96 11.21 33.433.0

15.5 86.1

DPF-65Luscar

A 16.8%M 3.01%

Diesel 1 31750

61100

20 92.2 98.97 10.610.7

37.036.3

18.5 85.5

DPF-66Luscar

A 16.8%M 3.01%

Diesel 2 31750

61100

20 92.6 98.71 10.9711.20

34.7833.4

21.0 87.7

DPF-67Pond

A 23.37% M 37%

Diesel 4 101750

61100

30 83.5 90.74 11.8812.48

49.246.6

11.2 65.29

DPF-68Pond

A 23.37% M 37%

Diesel 5 101750

61100

30 83.9 93.59 12.8813.67

44.941.5

11.0 71.19

47

Table A-1. Cont.

Test Feed CoalAsh&Moist

Oil MixType

OilAdditio

n%

MixerResTime

&rpm

Flot. CellResTime

&rpm

SolidsConcent.

%

Yield

%

Combust.Recovery %

Prod.Ash%

AshRed.%

FrothSolidsConcn

TailingsAsh%

DPF-69Pond

A 23.37% M 37%

D+MOleic Acid 0.5

2* 101750

61100

30 51.8 54.2 17.4418.1

25.422.6

7.58 28.0

DPF-70Pond

A 23.37% M 37%

D+MAerofroth 32 ml

2* 101750

61100

30 86.0 94.8 14.9415.3

36.134.5

8.68 69.2

DPF-71Pond

A 23.37% M 37%

D+MAerofroth 64 ml

2* 101750

61100

30 86.8 95.1 15.4515.8

33.932.3

8.32 71.4

DPF-72Pond

A 23.37% M 37%

D+MCalgon 0.05%

2* 101750

61100

30 77.4 87.8 12.2712.60

47.546.1

11.42 59.1

DPF-73Pond

A 23.37% M 37%

D+MUrea 0.5%

2* 101750

61100

30 66.5 74.1 13.3713.79

42.840.5

9.82 41.5

DPF-74Pond

A 23.37% M 37%

D+MUrea 1%

2* 101750

61100

30 68.4 76.0 13.6814.1

41.439.7

9.8 42.7

DPF-75Pond

A 23.37% M 37%

D+MO-Cresol 0.5%

2* 101750

61100

30 82.3 92.1 13.5713.9

41.940.5

14.0 65.5

DPF-76Pond

A 23.37% M 37%

D + MTween 0.0038%

2* 101750

61100

30 65.9 74.0 12.6513.04

45.944.2

9.07 40.8

DPF-77Pond

A 23.37% M 37%

Maya &Diesel (1:1)

2 101750

61100

30 71.0 76.7 16.0916.54

31.229.2

7.32 39.7

DPF-78Pond

A 23.37% M 37%

Maya &Diesel (1:1)

4 101750

61100

30 76.4 85.4 13.9914.76

40.137.0

8.69 48.5

DPF-78Pond,dupl

A 23.37% M 37%

Maya &Diesel (1:1)

4 101750

61100

30 79.2 86.7 14.4215.17

38.335.1

8.62 53.6

DPF-79Pond

A 23.37% M 37%

Maya &Diesel (1:1)

5 101750

61100

30 74.9 82.4 13.3814.4

42.738.4

9.90 47.4

DPF-79Pond,dupl

A 23.37% M 37%

Maya &Diesel (1:1)

5 101750

61100

30 75.0 81.8 14.0015.00

40.135.8

8.57 45.3

48

Table A-2. Comparison of the Pilot Plant and Batch Systems Performance Using the Very Same Feed Material

Test System Oil MixType

OilAddition

%

Feed CoalAsh%

SolidsConcent.

%

MixerRes, Time

min

Flot. CellResTime

&rpm

Yield

%

Combust.Recovery

%

ProductAsh%

AshReduction

%

TailingsAsh%

10:35 Plant 16.5 16.6 3 88.5 95.8 9.64 41.6 69.4

10:35 Batch Diesel 2.8 17.3 16.4 3 6/1100 89.5 97.3 9.93 42.540.5

77.9

11:35 Plant 16.8 15.8 3 88.2 96.4 9.04 46.2 74.7

11:35 Batch Diesel 2.8 16.8 15.4 3 6/1100 90.3 96.9 10.13 39.737.7

79.2

13:05 Plant 17.0 12.3 3 80.6 89.5 7.84 53.9 55.0

13.15 Batch Diesel 1.3 16.9 13.5 3 6/1100 83.5 91.0 9.06 46.445.8

55.3

13:45 Plant 20.1 19.5 3 66.7 76.9 7.88 60.8 44.6

13:40 Batch Diesel 0.85 20.1 16.5 3 6/1100 73.4 83.6 8.69 56.856.2

51.1

15:15 Plant 19.6 19.8 3 83.5 93.6 9.82 49.9 69.0

15:15 Batch Diesel 2.5 19.61 19.4 3 6/1100 87.7 96.3 10.92 44.042.1

77.1

15:40 Plant 19.0 18.3 3 83.2 93.4 9.08 52.0 68.1

15:35 Batch Diesel 2.6 19.0 19.4 3 6/1100 88.0 96.4 10.64 44.042.1

75.8

49

Table A-3 Coal Cleaning Process Test Conditions for Test L-1

Assumed Process ConditionsCoal Feed Rate, kg/h Slurry Solids Conc., % Oil Concentration, % Test Time, h

Period 1 200 20 0.4 1.5

CF 140 P 151 FW 116 FW 117 FS 201 FW 110 Samples Weight, g

Time kg/min (Oil) g/min L/min L/min L/min L/min S 200 S 201 S-501 S-502

14:00 Start 3.4 18 4.0 12 20 40

14:30 3.4 18 4.0 12 20 40

15:00 3.4 18 4.0 12 18 35 2208/360 1207/157 1924/98.1

15:30 3.4 18 4.0 12 18 30 1832/322 1349/202 2416/135

Table A-4. Coal Cleaning Process Test Conditions for Test L-2

Assumed Process ConditionsCoal Feed Rate, kg/h Slurry Solids Conc., % Oil Concentration, % Test Time, h

Period 1 250 25 0.4 1

Period 2 250 25 0.9 1



10:30 Start 4.1 17.8 4.0 9.0 15.0 40 wet/dry wet/dry wet/dry wet/dry

11:00 4.1 17.8 4.0 9.0 15.0 35 2236/572

11:15 4.1 17.9 4.0 9.0 15.0 36 1538/437

11:30 4.1 17.8 4.0 9.0 15.0 37 3488/991 960/77.2 28822/179.7

11:45 4.1 38.1 4.0 9.0 15.0 37 1728/483

12:00 4.1 38.3 4.0 9.0 15.0 38 1380/398 1145/495 2232/158

50

12:30 4.1 38.0 4.0 9.0 15.0 38 1262/352 596/188 2960/55.5


Assumed Process Conditions

Coal Feed Rate, kg/h Slurry Solids Conc., % Oil Concentration, % Test Time, hPeriod 1 190 16.4 1.5 3



10: Start wet/dry wet/dry wet/dry wet/dry

11:00 3.54 45.7 4.2 12 20 38 382/66 1705/309 872/258 2015/43.1

11:30 2.76 45.3 4.2 12 20 37 847/123 606/159 1448/25.4

12:00 3.09 44.9 4.2 10 19 37 802/133 977/156 633/190 1456/26.1

12:30 3.23 45.2 4.2 12 19 37 637/108 636/179 1010/19.1

13:00 3.00 44.9 4.2 12 19 37 1077/168 892/142 523/142 1110/18.5

13:30 3.22 44.8 4.2 12 19 37 635/107 488/136 1384/23.2

14:00 3.21 35.3 4.2 12 19 37 757/108 210/55 1576/31.7

51


Assumed Process ConditionsCoal Feed Rate, kg/min Slurry Solids Conc., % Oil Concentration, % Test Time, h

Period 1 190 15 3 2

Period 2 190 11-19 1.3 - 0.7 2Period 3 190 20 2.5 1.5



9:30 Start wet/dry wet/dry wet/dry wet/dry

10:00 2.94 84.0 4.0 12 18 37 976/157 - 493/136 1201/2.3

10:30 2.94 95.0 4.0 12 18 37 478/79.5 1074/176 551/155 1242/8.2

11:00 2.92 87.3 4.0 12 18 37 1175/181 - 586/158 1153/7.9

11:30 2.92 87.0 4.0 12 18 37 658/104 1095/169 468/131 1529/11.0

2.92 412:30 2.92 20.6 4.0 12 18 37 1295/147 - 831/156 1453/14.3

12:45 3.15 26.7 4.0 12 18 37 1039/117 - 494/103 1047/7.8

13:00 3.15 29.0 4.0 11 17 37 586/72.2 - 595/114 1120/10.7

13:15 3.15 29.1 4.0 11 17 37 831/112 1067/144 583/111 1586/

13:45 3.15 28.2 4.0 11 17 37 1122/219 - 731/177 1371/46.7

14:15 3.15 22.1 4.0 11 17 37 1338/248 1160/214 992/ 1346/77.9

14:30 3.15 84.0 4.0 11 17 37 1060/207 - 915/243 1077/14.5

14:45 3.15 83.5 4.0 11 17 37 1295/261 1058/205 731/207 1309/16.6

15:15 3.15 82.0 4.0 11 17 37 774/153 1059/206 462/130 1320/13.0

52

15:45 3.15 83.3 4.0 11 17 37 1458/267 1057/190 307/84 1390/21.2

poc-scale testing of oil agglomeration techniques …/67531/metadc... · poc-scale testing of oil...

Documents